Molecular and other biological evidence supports the recognition of at least three species of brown kiwi

Abstract

The presence of morphologically crypticlineages within the threatened brown kiwi ofNew Zealand has confounded their taxonomy. Recent genetic studies (Herbert and Daugherty1994; Baker et al. 1995) revealed that atleast two phylogenetic species exist within thebrown kiwi, and suggested that further researchshould resolve the taxonomic problems. In thispaper we extend genetic analyses to includesequences from 58 brown kiwi representing fivephylogenetic lineages for four mitochondrialloci (control region, cytochrome b,ATPase 6 and ATPase 8). Major lineages ofbrown kiwi are shown to be reciprocallymonophyletic, and align with other biologicaldifferences in the ecology, behavior,morphology and parasites of kiwi. BecausemtDNA sequences of major lineages of kiwi arenot evolving in a clocklike manner, we used anew penalized likelihood method withrate-smoothing to date the divergence of NorthIsland brown kiwi and the geographicallyisolated Okarito population (rowi) at about 6.2Mya. These lineages diverged about 8.2 Myafrom the brown kiwi in Fiordland and Haast inthe southern part of the South Island, and arethus older than the species of spotted kiwi(5.8 Mya). Given their distinctness, long-termgeographical isolation, lack of hybridizationin introduced populations, and accumulation ofnew biological characters within theselineages, we hypothesize that reproductiveincompatibilities have probably arisen as well. We therefore recommend that these divergentlineages be formally recognized as fullspecies; Apteryx mantelli should bere-instated for the North Island brown kiwi,A. australis should be restricted to thetokoeka, and a new species A. rowiishould be erected to describe the rowi atOkarito. Tokoeka should be split into at leastthree conservation management units (Haast,Fiordland and Stewart Island [Rakiura]), butfurther research is required to determine theexact relationships and status of theselineages. Further investigation is alsorequired into the genetic structuring of theNorth Island brown kiwi to confirm conservationmanagement units on the North Island.